This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Single Cylinder 25kW Range Extender: Development for Lowest Vibrations and Compact Design Based on Existing Production Parts
ISSN: 0148-7191, e-ISSN: 2688-3627
Published November 17, 2015 by Society of Automotive Engineers of Japan in Japan
Annotation ability available
The automotive trend towards increased levels of electrification is showing a clear direction for hybrid technologies. Nowadays Mild- and plug-in-hybrids open a very wide area of future developments whereas battery electric vehicles (BEV) are still evident but still perceived as niche products with limited production volumes. Nevertheless, major OEMs are working on these kinds of vehicles and have also brought such EV concepts into series production.
All of these designs show a clear trend that, beside the topic of electric traction motor and energy storage systems, the internal combustion engine (ICE) is also coming into focus again. In many of these vehicles the range extender (RE) unit is foreseen as an emergency unit to recharge the batteries if the state of charge (SOC) is too low.
One of the major advantages of a BEV over other designs is the very good acoustic behavior, so the NVH performance becomes the most challenging topic for RE development.
AVL has already investigated, published and partially also developed different types of RE units:
- single rotor Wankel 
- 2 cylinder inline 
- single cylinder 
Amongst others, a significant benefit of the single cylinder RE is the possible usage of parts from already existing powersports applications providing technology which typically is needed to fulfill the requirements of a BEV, such as:
- compact design
- good power to weight ratio
- high specific power
- good NVH behavior
- affordable production cost
- available industry (niche volume)
Rotax Engines of BRP-Powertrain GmbH & Co KG (BRP) fulfill the above mentioned aspects and therefore have been chosen to collaborate with the RE design.
This paper describes the general design features of the RE unit, how and which parts and systems could be taken over out of the existing BRP series product pallet. In addition first test bed results are shown in comparison with the simulations carried out in a previous development program.
The 3D CAD/simulations have shown that the desired power as well as the necessary small package requirements could be achieved whilst taking as many parts out of the ROTAX engine line-up as possible. Following these virtual studies, the engine was manufactured and tested on the dyno. These tests have confirmed the simulation results and especially the vibration investigations have shown an excellent engine mount excitation behavior compared to other RE concepts and standard 1 cylinder solutions.
CitationHubmann, C., Friedl, H., Gruber, S., and Foxhall, N., "Single Cylinder 25kW Range Extender: Development for Lowest Vibrations and Compact Design Based on Existing Production Parts," SAE Technical Paper 2015-32-0740, 2015, https://doi.org/10.4271/2015-32-0740.
- Range-Extender-Modul Wegbereiter für elektrische Mobilität MTZ 10 2009
- Two Cylinder Gasoline Engine Concept for Highly Integrated Range Extender and Hybrid Powertrain Applications SAE Paper 2010-32-0130
- Single Cylinder 25kW Range Extender as Alternative to a Rotary Engine Maintaining High Compactness and NVH Performance SAE Paper 2013-32-9132
- Kirchberger , R. Potential of a Range Extender Concept for Inner City Scooters - An Alternative to Pure Electric Mobility? Vienna Engine Symposium 2012
- Hohenberg , G. ; Beidl , C. Drehschwingungsberuhigung von Hybridantrieben mit niedrigen Zylinderzahlen Vienna Engine Symposium 2013
- Patent No1 210 245: Vibrationless Machines
- Rust , A. and Graf , B. NVH of Electric Vehicles with Range Extender SAE Int. J. Passeng. Cars - Mech. Syst. 3 1 860 867 2010 10.4271/2010-01-1404